Appeals

An appeal is decided by what you attach

Not by how well it argues. The reviewer is checking one thing: whether the item the denial asked for is now in front of them. Everything below is organised that way.

The five parts

  1. Who and what. Patient identifier, claim number, date of service, billed amount. The reviewer has to find the claim before anything else.
  2. The exact code you are appealing. Quote it as the remit prints it, group code and all: CO 197, not "the authorisation denial". One letter, one code.
  3. One sentence saying what you want. Reprocess and pay. Not a paragraph of context.
  4. The evidence that answers that code. The table below. This is the part that decides it.
  5. A date, and a copy kept. Appeal windows are short and the burden of proving you filed on time is yours.
Check it is an appeal before you write one. Some denials are corrections: the claim was wrong and needs resubmitting, not arguing. Appealing those spends the window and the deadline passes while you wait.

What each code actually needs

36 codes, with the documentation that wins each one. This is the same table the product uses when it reads an export.

DenialAttach this
CO 4
The procedure code and the modifier do not agree.
  • The correct modifier, supported by the documentation.
CO 5
The procedure does not match the place of service billed.
  • The schedule or encounter record showing where the service happened.
CO 6
The procedure does not fit the patient's age.
  • The corrected date of birth, or a code appropriate to the patient's age.
CO 8
The procedure does not match the provider type or specialty on file.
  • The correct taxonomy code, or the credentialing record for the rendering provider.
CO 11
The diagnosis does not match the procedure billed.
  • A recode from what the record actually documents.
CO 15
The authorisation number is missing, invalid, or does not match.
  • The correct authorisation number and its date range.
CO 16
Something the payer needed was missing or wrong on the claim.
  • A corrected claim with the missing element supplied.
OA 18
The payer treated this as an exact duplicate.
  • Documentation of the second, distinct service.
  • Modifier 76, 77 or 59 as appropriate to what actually happened.
OA 22
Another plan should pay first.
  • The primary payer's EOB, submitted with the claim as secondary.
OA 23
A prior payer already adjusted this, and that adjustment carries over.
  • The primary payer's EOB, attached to the secondary claim.
CO 24
The patient is in a capitated or managed-care plan, so this is paid under that contract.
  • Current eligibility showing which plan holds the contract on the date of service.
PR 27
Coverage had ended on the date of service.
  • Evidence another plan was active, and a rebill to that payer.
CO 29
Filed after the payer deadline.
  • A clearinghouse acceptance report carrying the original submission date.
  • The primary payer's EOB date, where the delay was theirs.
CO 31
The payer cannot find this patient as a member.
  • Current eligibility showing the correct member ID and plan.
PR 49
Treated as a routine or preventive service the plan does not cover.
  • The chart note showing a presenting complaint rather than a routine check.
CO 50
The payer decided the service was not medically necessary.
  • A chart note tied line-by-line to the payer's own policy criteria.
  • Objective findings: imaging, measured range of motion, strength testing.
  • Documented failure of conservative care, with dates.
CO 58
The payer decided the service should not have been done where it was done.
  • The admitting note explaining why the setting was clinically necessary.
  • The payer policy or criteria set they applied, so the appeal answers the right standard.
PR 96
Not a covered charge under this plan.
  • A signed ABN, which moves the balance to patient responsibility.
  • Whatever the RARC actually asks for, if it points at a documentation gap.
CO 97
The payer says this is already paid inside another service.
  • An operative or treatment note showing a separate site, session or encounter.
  • Modifier 59, or the more specific XE, XP, XS or XU.
CO 107
The related service this one depends on was not on the claim.
  • Both services on one claim, or the claim number of the primary procedure.
OA 109
Wrong payer or wrong contractor for this claim.
  • Identification of the correct payer, and a rebill to them.
PR 119
The benefit maximum for this period has been reached.
  • A KX modifier where continued therapy is medically necessary and documented.
  • Documentation supporting a medical-necessity exception.
CO 146
The diagnosis was not valid on that date of service.
  • The diagnosis code valid on the date of service.
CO 151
The payer says the records do not support this many units or visits.
  • Daily treatment notes with start and stop times, or total timed minutes.
  • The plan of care showing the frequency was ordered and justified.
CO 167
The diagnosis billed is not covered for this service.
  • A covered diagnosis that is already documented in the note, if one exists.
  • Otherwise, an appeal on the merits citing the policy.
CO 170
This payer does not pay this service when this type of provider performs it.
  • Documentation supporting incident-to billing, where the requirements were genuinely met on the day.
CO 181
The procedure code was not valid on that date of service.
  • The procedure code valid on the date of service.
CO 185
The rendering provider is not eligible to perform the service billed.
  • The credentialing approval letter with its effective date.
  • The payer's own provider record showing the taxonomy.
CO 197
The payer says no prior authorisation was on file.
  • The authorisation number and its approval date.
  • The retro-authorisation request and the payer's response to it.
  • Documentation that the service was urgent or emergent, where the payer waives auth for those.
CO 198
Authorised, but more units or visits were billed than approved.
  • Treatment notes showing medical necessity for the units beyond the approval.
  • A re-authorisation request covering the additional units.
PR 204
Not covered under the patient’s current benefit plan.
  • An ABN signed before the service was delivered.
CO 226
The payer asked you for information and did not get it, or did not get enough.
  • The payer's original request letter, which says what and by when.
  • Proof of what was sent and when, including the transmission record.
CO 234
This procedure is not paid separately.
  • Documentation supporting a modifier, where the policy allows one.
CO 236
This procedure and another one billed the same day cannot be billed together under NCCI.
  • The operative or procedure note showing the two services were distinct in site, session or encounter.
  • The NCCI edit table entry with its modifier indicator.
CO 242
The provider was out of network, or not the patient's assigned primary care provider.
  • The referral or authorisation, with its date range.
  • Documentation that the care was emergent, where that applies.
  • The network participation record for that specific plan product.
CO B7
The provider was not certified or eligible for this service on that date.
  • The effective date of enrolment, once corrected.
  • An appeal covering the retroactive period the payer allows.

How long you have

We are not going to print a number here, and you should distrust sites that do. An appeal window is set by your contract with that payer. It is not the same as the timely filing limit for an original claim, it differs by plan and by product line within the same payer, and it changes.

Look in this order:

  1. Your payer contract. It governs, and it is the only source that binds them.
  2. The provider manual for that plan, which usually restates it.
  3. The remittance advice itself. Many payers print the appeal window on the remit that carried the denial.
  4. Your state's prompt-pay statute, which sometimes sets a floor the contract cannot go under.

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